21695407 has 2 divisors, whose sum is σ = 21695408. Its totient is φ = 21695406.

The previous prime is 21695389. The next prime is 21695423. The reversal of 21695407 is 70459612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21695407 - 2¹⁹ = 21171119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21695467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10847703 + 10847704.

It is an arithmetic number, because the mean of its divisors is an integer number (10847704).

Almost surely, 2^21695407 is an apocalyptic number.

21695407 is a deficient number, since it is larger than the sum of its proper divisors (1).

21695407 is an equidigital number, since it uses as much as digits as its factorization.

21695407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 21695407 is about 4657.8328651853. The cubic root of 21695407 is about 278.9047648818.

The spelling of 21695407 in words is "twenty-one million, six hundred ninety-five thousand, four hundred seven".